When sending automated messages from Delta PMS to guests who booked via Booking.com,
you may include links such as your Pre Check-in Form in the message body.
However, for security reasons, Booking.com automatically blocks any links that are not on its approved “safe list.”
To ensure your message is delivered correctly, you must register Delta PMS URLs on Booking.com’s whitelist beforehand.
🔹 What Is a “Whitelist”?
The whitelist is Booking.com’s list of approved links.
Only URLs registered here are considered “safe,” meaning they can be shown to guests in messages.
If the URL is not added to the whitelist, Booking.com may remove the link or hide it from your guest messages, even if it’s legitimate.
🔹 How to Register the Link (Booking.com Extranet)
Log in to your Booking.com Extranet
From the top menu, go to [Property] → [Messaging preferences]
Open the [Security settings] tab
Scroll down to “Your approved links”
Click [Add a link] and add the following URLs:
guest.deltahq.com
✅ After Registration
Once these URLs are added, Delta PMS messages containing your Pre Check-in Form link will be delivered correctly to Booking.com guests.
This setup only needs to be done once per Booking.com account, and it will apply to all messages sent from that account.